Multi-stage angle drive reduction gear box

Abstract: The reduction gear box comprises a housing (2), an input shaft (3) having its longitudinal axis (A) horizontal and coupled to a drive shaft, an output shaft (4) having its longitudinal axis (B) horizontal and coupled to a utiliser shaft, and several drive reduction stages within the housing between the input shaft and the output shaft. One stage (21) after the first stage includes a gear pair constituted by a hypoid bevel pinion and a bevel crown gear (26) with mutually perpendicular axes, the axis (C) of the pinion being offset from the axis (B) of the crown gear by a distance (X) such that the axes (A and B) of the input shaft and of the output shaft intersect at right angles and lie in the same horizontal plane.

Description: The present invention relates to a multi-stage angle drive reduction gear box. It is known that reduction gear boxes of the type mentioned above include a reduction gear housing, a motor-driven input shaft, an output shaft with its axis perpendicular to that of the input shaft, and several drive reduction stages between the said shafts, which stages are installed in the housing. A reduction gear box with the features of the preamble of claim 1 is known from NL-A-8 001 384. One of the main disadvantages of the reduction gear boxes described above lies in the fact that longitudinal axes of the input and output shafts lie in different planes whereby the axis of the engine drive shaft coupled to the input shaft is at a higher (lower) level than the utiliser shaft coupled to the output shaft. All this constitutes a limitation on the use of such gear boxes. In fact, when it is wished to transmit drive to the utiliser shaft in the reverse sense from previously it is necessary to use a second reduction gear box which is arranged internally so as to cause the output shaft to rotate in the reverse sense. It is for this reason that the attachment means for fixing the reduction gear housing to a fixed frame are formed in a single, predetermined horizontal wall of the housing itself. The object of the present invention is to provide a multi-stage angle drive reduction gear box in which the longitudinal axes of the input and output shafts lie in the same horizontal planes. Further objects and advantages of the present invention will become apparent during the course of the description which follows. On the basis of the present invention, a multi-stage angle drive reduction gear box is formed of the type comprising: a reduction gear housing; an input shaft with its longitudinal axis horizontal coupled to a drive shaft of an engine; an output shaft with its longitudinal axis horizontal coupled to a utiliser shaft; and a plurality of drive reduction stages defined within the housing between the input shaft and the output shaft; characterised in that one of the reduction stages after the first stage includes a gear pair constituted by a hypoid bevel pinion and a bevel crown gear with mutually perpendicular axes, the axis of the pinion and the axis of crown gear being offset from each other, the offset being such that the axes of the input shaft and the output shaft intersect at right angles and lie in the same horizontal plane. For a better understanding of the present invention, one preferred embodiment will now be described purely by way of non-limitative example, with reference to the appended drawings, in which: Figure 1 is a perspective view of a multi-stage angle drive reduction gear box formed in accordance with the present invention; Figure 2 is a longitudinal section through the reduction gear box of Figure 1; Figure 3 is a front view of the reduction gear box of Figure 1; and Figure 4 is a section taken on the line IV-IV of Figure 2. As illustrated in Figure 1, a multi-stage angle drive reduction gear box is generally indicted 1 and includes: a reduction gear housing 2; an input shaft 3 arranged with its longitudinal axis A horizontal and coupled in a manner not illustrated to a drive shaft of an engine not illustrated; an output shaft 4 arranged with its longitudinal axis B horizontal and coupled in a manner not illustrated to a utiliser shaft not illustrated; and a plurality of drive reduction stages defined within the housing 2 between the shaft 3 and the shaft 4. As is known, in use, the shaft 3 is driven by a drive shaft of an engine not illustrated and the shaft 4 drives a shaft of a utiliser not illustrated. With reference to Figures 1 and 2, the housing 2 comprises: a front wall 5 which lies in a vertical plane; a rear wall 6 parallel to the wall 5; two side walls 7 which lie in respective vertical planes which are parallel to each other and perpendicular to the planes in which the walls 5 and 6 lie; a lower (upper) wall 8 which lies in a horizontal plane; and an upper (lower) wall 11 parallel to the wall 8. The walls 5, 6, 7, 8 and 11 have rectangular peripheral shapes. The walls 8 and 11 are both adapted to be fixed to a support frame, not illustrated. More particularly the walls 8 and 11 are each made with two integral, thickened portions 9 on their outer faces, in positions symmetrical with each other and in which respective through-holes 10 are formed for receiving screws for fixing the walls the said support frame, not illustrated. In essence, the reduction gear box 1 is fixed to the frame by means of the said screws either in the wall 8 or in the wall 11, whichever is used as the base. With reference to Figures 1 and 2, the axes A and B are perpendicular to each other and lie in the same horizontal plane parallel to the walls 8 and 11 and, in particular, in an intermediate position between these walls 8 and 11. Moreover the axis A passes through the geometric centre of the wall 5. With reference to Figures 1, 2 and 3, the shaft 3 projects into the housing 2 through the wall 5. More particularly the wall 5 has a through-hole 12 on the axis A in which there is fitted a tubular body 13 aligned with the axis A. An annular flange 14 projects from the body 13 and is fixed by screws to the outer face of the wall 5. The shaft 3 passes through the body 13 and one end thereof projects into the housing 2; ball bearings 15 are provided between the inner surface of the body 13 and the shaft 3. With reference to Figures 2, 3 and 4, in this embodiment, the shaft 4 has respective portions 4a and 4b projecting through both walls 7. Respective through-holes 16 are formed in these walls 7 on the axis B; respective roller bearings 17 are mounted in the holes 16. With reference to Figures 1 and 2, in this embodiment, the reduction gear box 1 has two reduction stages 18 and 21 within the housing 2. The stage 18 is constituted by the meshing of a spur gear 22 formed on the inner end of the shaft 3 and a spur gear 23, of larger diameter, keyed on to a rotatable shaft 24 arranged with its longitudinal axis C horizontal. The stage 21 is constituted by the meshing of a hypoid bevel pinion 25 keyed on to the rotatable shaft 24 and a bevel crown gear 26 keyed on to the central part of the shaft 4. The shaft 24 is supported by a tubular body 27 formed integrally with the housing 2; two roller bearings 28 are provided between the inner surface of the body 27 and the shaft 24. With reference to Figure 2, it should be stressed that the stage 21 utilises a gear pair constituted by the pinion 25 and the crown gear 26 arranged with their axes mutually perpendicular and with the axis C of the pinion 25 offset from the axis B of the crown gear 26 by a distance X (Figure 3). The stage 18 uses a gear pair constituted by the spur gear 22 and the spur gear 23 which have an interaxial spacing Y such that the projection of this interaxial spacing Y in the direction of the offset X between the axis C of the pinion 25 and the axis B of the crown gear 26 is equal to the offset X itself, whereby the axis A intersects the axis B. The advantages achieved by the embodiment of the present invention will be clear from the description above. In particular, a reduction gear box is realised in which the axes of the input shaft and the output shaft intersect at right angles to each other and lie in the same horizontal plane. For this reason, the engine and the utiliser being in the same given positions, the reduction gear box may couple the shaft 4 and to the utiliser shaft by means of either one of its two portions 4a and 4b according to the sense of rotation of the drive to be transmitted to the utiliser shaft while preserving the same geometry of attachment to the engine and utiliser shafts. In essence the reduction gear box which is the subject of the present invention may have the wall 8 as the base wall fixed to the support frame to transmit drive to the utiliser shaft in one predetermined sense of rotation or may have the wall 11 as the base wall fixed to the support frame to transmit drive to the utiliser shaft in the reverse sense, and this without any modification to the interior of the reduction gear box. The reduction gear box which is the subject of the present invention can operate as two current reduction gear boxes whereby it is clear that, in addition to reducing costs to the purchaser, it achieves a considerable saving in construction costs since it is not necessary to modify the reduction gear box according to the sense of rotation to be transmitted to the utiliser shaft. Finally it is clear that modifications and variations may be made to the reduction gear box 1 described and illustrated without thereby departing from the protective scope of the present invention. In particular, the shaft 4 could be hollow and be contained within the housing 2, the connection of the portion 4a or 4b to the utiliser shaft being formed within the housing 2. The hollow shaft 4 is as practical and has the same advantages as the shaft 4 illustrated in the appended drawings. In addition, the shaft 4 could have only one portion projecting from the housing 2. There may be a greater number of reduction stages within the housing 2 than that described and illustrated. In this case the stage 21 could be any stage after the first stage and the offset X between the axis C of the pinion 25 and the axis B of the crown gear 26 must be equal to the algebraic sum of the projections in the direction of the offset X of the interaxial spacings Y defined in all the other reduction stages.

Claims: A multiple-stage angle drive reduction gear box of the type comprising : a reduction gear housing (2); an input shaft (3) with its longitudinal axis (A) horizontal coupled to a drive shaft of an engine; an output shaft (4) with its longitudinal axis (B) horizontal coupled to a utiliser shaft; and a plurality of drive reduction stages defined within the housing (2) between the input shaft (3) and the output shaft (4); wherein one (21) of the reduction stages after the first stage includes a gear pair constituted by a hypoid bevel pinion (25) and a bevel crown gear (26) with mutually perpendicular axes, the axis (C) of the pinion (25) and the axis (B) of crown gear (26) being offset by a distance (X), characterised in that the offset (X) is such that the axes (A and B) of the input shaft (3) and the output shaft (4) intersect at right angles and lie in the same horizontal plane. A reduction gear box according to Claim 1, characterised in that the housing (2) includes a front wall (5) which lies in a vertical plane and through which the input shaft (3) extends into the housing (2), a rear wall (6) parallel to the front wall (5), two side walls (7) which lie in respective vertical planes parallel to each other and perpendicular to the planes in which the front and rear walls (5 and 6) lie, a lower (upper) wall (8) which lies in a horizontal plane, and an upper (lower) wall (11) parallel to the lower (upper) wall (8); the horizontal plane in which the said axes (A and B) of the input shaft (3) and the output shaft (4) lie being parallel to the lower (upper) wall (8) and to the upper (lower) wall (11) and located intermediate the lower (upper) wall (8) and the upper (lower) wall (11). A reduction gear box according to Claim 2, characterised in that the longitudinal axis (A) of the input shaft (3) passes through the geometric centre of the front wall (5). A reduction gear box according to any one of the preceding claims, characterised in that the output shaft (4) has a portion which projects out of the housing (2) through one of the side walls (7). A reduction gear box according to any one of Claims 1 to 4, characterised in that the output shaft (4) has two portions (4a and 4b) which project out of the housing (2) each through a respective one of the side walls (7). A reduction gear box according to any one of Claims 1 to 4, characterised in that the output shaft (4) is hollow and is contained within the housing (2). A reduction gear box according to any one of the preceding Claims, characterised in that both the lower (upper) (8) and upper (lower) (11) walls have means (9 and 10) for fixing them to a support frame. A reduction gear box according to any one of the preceding Claims, characterised in that it includes several reduction stages of which the said stage (21), after the first stage, includes the gear pair constituted by the pinion (25) and the crown gear (26) the axes of which are offset by the distance (X), this offset (X) being equal to the algebraic sum of the projections in the direction of the offset (X) of the interaxial spacings (Y) defined in all the other reduction stages. A reduction gear box according to any one of Claims 1 to 8, characterised in that it includes two reduction stages (18 and 21), of which the first stage (18) comprises a gear pair defined by a spur gear (22) formed on the inner end of the input shaft (3) and a spur gear (23) of a different diameter keyed onto a rotatable shaft (24) with its longitudinal axis (C) horizontal and the second stage (21) includes the said pinion (25) keyed on to the said shaft (24) and the crown gear (26) keyed on to the central part of the output shaft (4).

Inventors: DEPIETRI PIETRO, DEPIETRI, PIETRO
Applicants: BONFIGLIOLI RIDUTTORI SPA, BONFIGLIOLI RIDUTTORI S.P.A.
Application year: 1994
Main classification: F16H1
IPC codes: F16H1, F16H57